1. Field of the Invention
The present invention relates to a clutch mechanism for a lock. In particular, the present invention relates to a clutch mechanism for a lock that allows the outer handle to rotate freely when the lock is in a locked state so that the internal parts of the lock will not be damaged.
2. Description of the Related Art
A conventional door lock generally includes an outer handle and an inner handle respectively attached to the outside and the inside of a door so that the latch bolt can be retracted by turning either one of the outer handle and the inner handle. When in a locked state, the outer handle could not be turned for retracting the latch bolt. It is, however, not uncommon that the user still applies force to the outer handle to an extent that is normally sufficiently large enough for retracting the latch bolt if the user is not aware of the locked state of the lock. Thus, the inner parts of the lock connected to the handle could be damaged by a torque resulting from the force applied to the outer handle. The situation worsens for a lock with lever type handles.
U.S. Pat. No. 6,041,630 discloses a lock having a clutch mechanism to solve this problem. The lock includes an inner handle having a locking bar received therein and an outer handle connected to a spindle with a retaining base received therein which has two first grooves defined therein. A cam is connected to the retaining base and has two second grooves which communicate with the first grooves so that a locking piece is movably received between the retaining base and the cam with a spring biased between the locking piece and the retaining base. The locking piece has two flanges movably received in the first grooves and the second grooves. A slide is movably received in the cam and contacts the locking piece at one end thereof and the locking bar at the other end thereof so that the two flanges of the locking piece are disengaged from the second grooves when the locking bar is pushed. Therefore, the outer handle can be freely rotated. Nevertheless, there are too many elements for the clutch mechanism. The assembly procedure is too complicated and the overall cost is increased. Further, the lock can only be mounted to a door with a standard thickness.
U.S. Pat. No. 6,364,383 discloses a door lock that allows adjustment of longitudinal position of an outside rose and an adjusting sleeve relative to the outside seat to suit a thickness of a door to which the door lock is mounted. The door lock also provides a burglar-proof effect for the outside rose assembly by means of providing an anti-torque ring.
The present invention is intended to provide a clutch mechanism for a lock that allows the outside handle to turn freely when the lock is in a locked state.
An object of the present invention is to provide a clutch mechanism for a lock that allows the outside handle to rotate freely when the lock is in a locked state so that the internal parts of the lock will not be damaged even though an excessive force is applied to the outside handle.
Another object of the present invention is to provide a clutch mechanism for a lock that allows the outside handle to rotate freely while allowing adjustment of the lock to suit a thickness of a door to which the door lock is mounted.
In accordance with an aspect of the invention, a lock comprises:
a latch;
a retractor for retracting the latch;
an inside handle;
an inside spindle having a first end fixed to the inside handle to turn therewith and a second end, the inside spindle being operably connected to the retractor such that rotation of the inside spindle causes retraction of the latch;
a locking bar extending through the inside spindle;
an inside hub for rotatably receiving the second end of the inside spindle;
an outside handle;
an outside spindle having a first end and a second end fixed to the outside handle to turn therewith;
an outside hub for rotatably receiving the first end of the outside spindle;
a cam received in the first end of the outside spindle, the cam including a first end and a second end, a lug being formed on the first end of the cam and operably connected to the retractor, an elastic element being received in the cam, a peg being mounted in the cam; and
a sleeve received in the cam and slidable along a longitudinal direction of the outside spindle, the sleeve including a longitudinal slot having an enlarged section, the peg being received in the longitudinal slot of the sleeve, the sleeve being engaged with the outside spindle to turn therewith while allowing the sleeve to move longitudinally in the cam;
wherein when the locking bar is moved to a locking position, the peg is located in the enlarged section such that the sleeve and the outside spindle turn freely without causing rotation of the cam when the outside spindle is turned.
In an embodiment of the invention, the first end of the outside spindle includes a slot in an end face thereof. The slot extends along the longitudinal direction of the outside spindle. The sleeve includes an arm extending therefrom, with the arm extending into the slot of the outside spindle and longitudinally slidable along the slot.
The outside hub includes a restraining recessed portion and the arm extends into the restraining recessed portion. The restraining recessed portion has two ends for limiting rotational movement of the arm. The first end of the sleeve includes a hole for securely engaging with an end of the locking bar.
The cam includes an engaging portion and the outside handle includes a cylinder mounted therein. The cylinder includes a cylinder bar engaged with the engaging portion of the cam, allowing joint rotation of the cylinder bar and the cam.
The outside hub includes an outside seat that has an outer threading with two diametrically disposed flat surfaces. A reinforcing ring includes two positioning posts extending outward therefrom and two diametrically disposed flat sections in an inner periphery delimiting a hole thereof. The reinforcing ring is mounted around the outside seat, with the flat sections of the reinforcing ring being in contact with the flat sections of the outside seat. An adjusting sleeve includes an inner threading threadedly engaged with the outer threading of the outside seat. An outside rose is mounted to the outside handle. The adjusting sleeve is securely engaged with the outside rose such that rotation of the outside rose causes longitudinal movement of the adjusting sleeve and the outside rose until the retractor is located in a center of a thickness of a door to which the lock is mounted.
Each positioning post of the reinforcing ring has a screw hole. An inside rose liner is mounted around the inside hub and includes at least one pair of positioning holes, with two screws extending through one pair of the positioning holes of the inside rose liner into the screw holes of the positioning posts of the reinforcing ring. The inside rose includes a threaded inner periphery for engaging with an outer threading on the inside hub. The outside rose includes a central stepped portion having a central through-hole. The adjusting sleeve has an end securely engaged with the central stepped portion of the outside rose.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.